1. Field of the Invention
The present invention generally relates to a grouping method used in image processing, and in particular, to a method of grouping rendering data in an information processing system such as a personal computer.
2. Description of the Related Art
In recent years, distributed processing using a multi-central processing unit (CPU) has been utilized in a computing machine terminal such as a personal computer and a workstation.
However, with respect to rendering data transferred by an application, a processing process is not considered. Accordingly, distributed processing using a multi-CPU and plural modules cannot be effectively performed.
In order to perform distributed processing, a grouping of rendering data may be necessary.
Japanese Patent Application Laid-Open No. 2004-193876 discusses a method of grouping rendering data that has overlapping regions.
FIG. 16 is a diagram illustrating a conventional method of grouping rendering data.
In the conventional method of grouping, however, only rendering data having overlapping regions is grouped.
In the conventional grouping method, the produced groups may not obtain sufficient advantage of the distributed processing of rendering data.
In this regard, to describe broadly, there are two methods for the rendering processing of rendering data.
Namely, there are a scanline algorithm and a painter's algorithm.
In the scanline algorithm, each rendering data is divided per each scan line (group of pixels in a horizontal direction) (resulting divided data is called a “segment”).
Then, values of depth (Z-axis values) of the segments that share the same scan line are compared to each other, and only the segment that is positioned closer to the front (that is, the segment that is higher in the Z-axis) is rendered.
In the scanline algorithm, this processing is performed on all of the scan lines on a screen.
Note that the scanline algorithm is effective for rendering complicated rendering data that has very many overlapping regions.
However, the speed of processing texts when the scanline algorithm is used is slow because texts have very many edges.
On the other hand, in the painter's algorithm, objects are rendered in the order from an object positioned closer to the back (lower in the Z-axis) to an object positioned closer to the front.
The painter's algorithm is effective in rendering the rendering data that has fewer overlapping regions.
However, in rendering the rendering data that has many overlapping regions, it takes long time to perform the processing, and transmission processing cannot be performed.
Thus, with respect to a group formed by grouping rendering data having overlapping regions, as used in the conventional grouping method, processing cannot be effectively and appropriately performed even using any one of the above-described rendering methods.